AWS CDK is open source tool, written in TypeScript languages.
To support other languages it is using "jsii" library
The AWS Cloud Development Kit (AWS CDK) is an open-source software development framework to define cloud infrastructure in code and provision it through AWS CloudFormation.
It offers a high-level object-oriented abstraction to define AWS resources imperatively using the power of modern programming languages. Using the CDK’s library of infrastructure constructs, you can easily encapsulate AWS best practices in your infrastructure definition and share it without worrying about boilerplate logic.
jsii
allows code in any language to naturally interact with JavaScript classes. It is the technology that enables the AWS Cloud Development Kit to deliver polyglot libraries from a single codebase!
A class library written in TypeScript can be used in projects authored in TypeScript or Javascript (as usual), but also in Python, Java, C# (and other languages from the .NET family)
docs: aws.github.io/jsii/
How the jsii open source framework meets developers where they are @ AWS blog
Generate Python, Java, and .NET software libraries from a TypeScript source